Nothing sketchy about self hosting your email. Sure, that is what the big tech cartel wants you to think so you're forced to let them handle your correspondence "for your own safety". Don't believe their lies.
They had one of the cheapest registration costs. And so ended up with a high concentration of spammers compared to older established tld’s like dot com. Using the tld for legitimate purposes is really challenging due to the high number of systems that flat out blacklist it.